Added support of proxy digest authentication
make invisible significant distictions explicit, and assorted whitespace normalizations
Merge commit 'a9416a8a894943a6e7f6cc484c' into digest-auth
fallback to RFC 2069 behaviour if qop isn't given
add loopback tests for digest proxy auth
add digest_auth reader
test for correct credential reuse
reuse credentials for proxy digest auth
reuse credentials for proxy basic auth
add test for RFC 2617 conformant auth method selection
add comment
test digest proxy auth with a real proxy
return the response at the target of a redirect
use old style hash syntax
Accept an array of strings (and IO-likes) as a query value.

e.g. `{ x: 'a', y: [1,2,3] }` is encoded into `"x=a&y=1&y=2&y=3"`.
actually use the proxy in the proxy digest auth test
Make test runnable even if simplecov is not installed
Allow body for DELETE

entity-body is not explicitly prohibited in spec for methods other than
HEAD and TRACE.  Allow DELETE to have body as the second argument (or
:body parameter).

Also explicitly add 'Content-Type: application/x-www-form-urlencoded'
header if entity-body is encoded in x-www-form-urlencoded. This affects
all methods not only for DELETE.

Fixes #102.
Avoid Hash order dependency

Test failure in cf6bd14fd15969f75df1cc13495990d3c1cbff46. Thanks
BuildHive and TravisCI!
Fill request parameters in response Message::Header

Just transplant req.header.(request_method,request_uri,request_query) to
res.header.  Fixes #97.